Host plants enzyme induction

Induction of MFO activity in insects to synthetic insecticides was discovered nearly two decades ago. This phenomenon as mediated by natural plant products has received increased attention in the last few years. Induction refers to the temporarily accelerated production of enzyme protein. A large number of natural plant chemicals are known to induce the MFO system (Brattsten et al., 1977) and host plant allelochemic induction of MFO activity may mediate resistance to synthetic insecticides as well (Yu etal., 1979). There can also be genetic bases to cross-resistance between pesticides and plant defenses (Gould et al., 1982), thus posing another significant consideration in breeding host plant resistance. 

Botrytis cinerea is responsible for gray mold disease in more than 200 host plants. This necrotrophic fungus displays the capacity to kill host cells through the production of toxins and reactive oxygen species and the induction of a plant-produced oxidative burst. Thanks to an arsenal of degrading enzymes, B. cinerea is then able to feed on various plant tissues (Choquer and others 2007). 

Yu SJ (1983) Induction of detoxifying enzymes by allelochemicals and host plants in the fall armyworm. Pestic Biochem Physiol 19 330-336 Yu SJ (1984) Interactions of allelochemicals with detoxification enzymes of insecticide-susceptible and resistant fall armyworms. Pestic Biochem Physiol 22 60-68 Yu SJ (1986) Consequences of induced foreign compound-metabolizing enzymes in insects. In Brattsten LB, Ahmad S (eds) Molecular aspects of insect-plant associations. Plenum, New York, pp 153-174... 

Yu S. J. (1983) Induction of detoxifying enzymes by allelochemicals and host plants in the fall armyworm. Pest. Biochem. Physiol. 19, 330-336. 

They act as antipathogenic agents and thus affect the process of pathogenesis. They may act on the host through the Induction of plant resistance mechanisms such as stimulation of lignification or enhancement of phytoalexin production. (Please refer to the chapter by Salt and Kuc in this volume for further discussion of this type of compound.) They may act on the pathogen to accentuate elicitor release or to prevent infection (host penetration), colonization (inhibition of phytotoxin synthesis, extracellular enzyme production and action, or phytoalexin degradation) or reproduction. 

In the case of certain bark beetles a number of their identified pheromones are derivatives of a-pinene 136, 373, 435), and it is probably correct to assume that these derivatives arise by enzymatic action on the a-pinene of the host plant. There are two possibilities for the origin of the enzymes concerned. Firstly, they could be secreted by the gut tissue of the insect and effect the transformation of a-pinene in this region. The induction of mixed-function oxidases in insect gut tissue by host plant monoterpenes has been mentioned. Secondly, they could be produced by microorganisms present either within the gut or in the host plant tissue itself or in the frass after excretion. It is the second possibility that concerns us now. 

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